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CALIFORNIA GEOLOGICAL SURVEYJOHN G. PARRISH, Ph.D., STATE GEOLOGIST
CGS SPECIAL REPORT 217, PLATE 8GEOLOGIC COMPILATION OF QUATERNARY SURFICIAL DEPOSITS IN SOUTHERN CALIFORNIA
ONSHORE PORTION OF THE LONG BEACH 30' x 60' QUADRANGLESTATE OF CALIFORNIA - ARNOLD SCHWARZENEGGER, GOVERNOR
THE RESOURCES AGENCY - LESTER SNOW, SECRETARYDEPARTMENT OF CONSERVATION - BRIDGETT LUTHER, DIRECTOR
GEOLOGIC COMPILATION OF QUATERNARY SURFICIAL DEPOSITS IN SOUTHERN CALIFORNIAProjection: Universal Transverse Mercator, Zone 11 North, North American Datum of 1983.Topographic contours derived from USGS 1/3 arc-second National Elevation Dataset (NED). Shaded topographic relief derived from USGS 1 arc-second NED. Base map of hydrography from National Hydrography Dataset Plus (NHDPlus) and California Department of Fish and Game. Base map of geographic names from USGS Geographic Names Information System (GNIS).
MAP LOCATION
CALIF. ONSHORE PORTION OF THE LONG BEACH 30' X 60' QUADRANGLE
MAP REFERENCES
This map of Quaternary surficial deposits in the Long Beach 30’ x 60’ quadrangle was compiled by theCalifornia Geological Survey (CGS) for the Department of Water Resources (DWR) to assist in identifying whereflooding and deposition of sediment occurred in the geologically recent past. The focus of this project is onQuaternary (Q) surficial deposits (less than 1.8 million years) on alluvial fans, floodplains, and in basins wheresuch deposits are subject to a number of geologic hazards including flooding, amplification of seismic shaking,liquefaction, and collapsible soils. In general, areas of most recent deposition during Late Holocene time (withinthe last 500 years) have a greater potential to be areas of future flooding and deposition than those underlain byolder surficial deposits. Project Overview The Long Beach 30’ x 60’ quadrangle represents one of several 100,000 scale quadrangles included in thedetailed Geographic Information System (GIS) based geologic data set compiled by CGS from recent high resolutiongeologic mapping available for southern California. The GIS database merges more than 2100 geologic units fromsource maps published primarily by the U.S. Geological Survey (USGS) and by CGS (Source GIS Database) into acommon format that depicts 40 derivative categories of surficial deposits and bedrock for the entire area(Derivative GIS Database). Quaternary surficial deposits are divided into 28 categories modified from themethodology of Matti and Cossette (2007), the Southern California Areal Mapping Project (SCAMP, 2000), and theUSGS and California Division of Mines and Geology (2000). While specific variations in age and physicalproperties exist within units on each source map, CGS retained the basic premise of Matti and Cossette (2007)that surficial deposits within each of the Quaternary derivative map units formed during a particular range ofgeologic time, have a similar origin, and have generally similar physical properties. Within the 28 derivativeunits, progressively older surficial deposits are typically better consolidated and more highly dissected byerosion, have more developed and/or eroded soil profiles with stronger degrees of weathering and surface armoring,and occupy a higher topographic position within alluvial fan and floodplain terrains. Geologic bedrock formationsfrom the source geologic maps are divided into 12 categories on the derivative maps, based on age and rock type.CGS rectified inconsistencies along the boundaries of mapped areas to create a seamless Derivative GIS Database,but retained links to the original mapping in the Source GIS Database so that the more detailed basic geologicinformation can be retrieved. Correlation of equivalent deposits across the whole southern California projectarea is represented in the GIS table entitled Correlation of Derivative and Source Geologic Map Units. Onshore Portion of the Long Beach Quadrangle The onshore portion of the Long Beach quadrangle lies predominantly within the Los Angeles Basin, located atthe northwestern end of the Peninsular Ranges geomorphic province. Most of the mapped area is underlain byQuaternary alluvial deposits, with modern beach and eolian (sand dune) deposits, older eolian deposits, marineterrace deposits, estuarine deposits, and large areas of artificial fill present along the western coastal plain
MAP EXPLANATIONDIGITAL GEOLOGIC DATA FILE USED IN GIS COMPILATION OF QUATERNARY UNITS Saucedo, G.J., Greene, H.G., Kennedy, M.P., and Bezore, S.P., 2009 (in progress), Geologic map of the Long Beach30' x 60' quadrangle, California: A digital database, http://conservation.ca.gov/cgs/rghm/rgm/Pages/preliminary_geologic_maps.aspx: California Geological Survey, Preliminary Geologic Map, scale 1:100,000. REFERENCES USED IN PREPARING LEGENDS AND MAPS FOR QUATERNARY UNITS Matti, J. C., and Cossette, P.M., 2007, Classification of surficial materials, Inland Empire Region, southern California:conceptual and operational framework: U.S. Geological Survey, Open-File Report (in progress). Southern California Areal Mapping Project (SCAMP), 2000, A proposed classification for surficial geologic materialsin southern California, version 1.0. U.S. Geological Survey and California Division of Mines and Geology, 2000, Classification of Quaternary deposits,Southern California Areal Mapping Project (SCAMP), a working model, version 1.0: (09/10/2000). OTHER REFERENCES CITED California Division of Mines and Geology, 1998a, Seismic hazard evaluation of the Inglewood 7.5-minute quadrangle,Los Angeles County, California: Open-File Report 98-18, 37 p., scale 1:24,000. California Division of Mines and Geology, 1998b, Seismic hazard evaluation of the Long Beach 7.5-minutequadrangle, Los Angeles County, California: Open-File Report 98-19, 39 p., scale 1:24,000. California Division of Mines and Geology, 1998c, Seismic hazard evaluation of the Los Alamitos 7.5-minutequadrangle, Los Angeles and Orange counties, California: Open-File Report 98-10, 27 p., scale 1:24,000. California Division of Mines and Geology, 1998d, Seismic hazard evaluation of the Redondo Beach 7.5-minutequadrangle, Los Angeles County, California: Open-File Report 98-22, 44 p., scale 1:24,000. California Division of Mines and Geology, 1998e, Seismic hazard evaluation of the Seal Beach 7.5-minutequadrangle, Los Angeles and Orange counties, California: Open-File Report 98-11, 37 p., scale 1:24,000. California Division of Mines and Geology, 1998f, Seismic hazard evaluation of the South Gate 7.5-minutequadrangle, Los Angeles County, California: Open-File Report 98-25, 25 p., scale 1:24,000. California Division of Mines and Geology, 1998g, Seismic hazard evaluation of the Venice 7.5-minute quadrangle,Los Angeles County, California: Open-File Report 98-27, 39 p., scale 1:24,000. Haydon, W.D., 2007, Landslide inventory map of the Palos Verdes Peninsula, Los Angeles, California: CaliforniaGeological Survey, Landslide Inventory Map Series, scale 1:24,000.
(California Division of Mines and Geology, 1998c, 1998d, and 1998f). In the eastern portion of the mapped area,relatively flat-lying Quaternary-age basin deposits, consisting of more than 4200 feet of partially consolidatedmarine and nonmarine sediments, end abruptly on the west side of the basin at the Newport-Inglewood uplift, whichruns through the center of the quadrangle (California Division of Mines and Geology, 1998a and 1998e). Olderalluvial fan deposits, associated with uplift along the Whittier Fault Zone, are present in the northeast cornerof the quadrangle. In the southern portion of the basin, extensive estuarine deposits and Holocene alluvium arepresent near the mouths of the Los Angeles, Rio Hondo and San Gabriel River systems (California Division of Minesand Geology, 1998a and 1998b). West of the Newport-Inglewood Fault Zone, the area is characterized by a series ofnorthwest-trending uplifted hills and broad coastal mesas (flat-topped hills), which are covered by marineterrace deposits and have been deeply incised by regional river systems. The marine terrace deposits areoverlain by a thin veneer of older alluvium composed of dense silty sand. Farther west, ancient dunes extendinland about two miles from the coast (California Division of Mines and Geology, 1998g). To the southwest, thePalos Verdes Hills form a northwest-trending dome-like ridge that extends across the Palos Verdes Peninsula andis underlain primarily by Tertiary sedimentary and volcanic bedrock. Landscape in this area is characterized bya series of elevated step-like wave-cut marine terraces, steep cliffs and headlands along the coast, and massiverecently active and ancient landslides (Haydon, 2007). The terraces are generally covered by a nonmarine veneerover thin marine deposits. Alluvium and slope wash deposits are present within the major drainages of thepeninsula. In preparing this derivative map of the onshore portion of the Long Beach 30’ x 60’quadrangle, CGS usedgeologic source data compiled in digital format by Saucedo and others (2009). CGS retained the boundaries ofQuaternary age surficial deposits shown on the source map with very few revisions. Quaternary surficial depositson the source map are represented on this map by 16 of the 28 generalized project derivative units; boundaries ofmore detailed source map subdivisions are shown without label within the generalized derivative unit. Thisindicates more detailed geologic information is available in the Source GIS Database. For example, an areadesignated Qyf (young alluvial fan deposits) on this map may have been further divided on the source map intoseveral units to distinguish different depositional surfaces and compositions. Bedrock units identified bySaucedo and others (2009) are represented on this map by 6 of the 12 project derivative bedrock units (see MapUnits and Correlation of Map Units). Quaternary surficial deposits and geologic formation names originallycompiled by Saucedo and others (2009) are correlated with derivative categories used by CGS in the Geologic LabelsGIS spreadsheet for the Long Beach quadrangle. This map, along with others in the Geologic Compilation of Quaternary Surficial Deposits in SouthernCalifornia Derivative GIS Database, is regional in nature and should not be used as a substitute for detailedgeologic studies in any specific area. It is intended only for rapid identification of areas subject to previousand potential future flooding and other geologic hazards on alluvial fans and floodplains.
INDEX TO USGS 7.5' QUADRANGLES
APPROXIMATE MEANDECLINATION, 2010
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A A
TRUE
NOR
TH
MAGN
ETIC
NOR
TH
12 1 2/
[For geologic line symbols: lines are solid where location is accurate, long-dashed where location is approximate, short-dashed where location is inferred, dotted where location is concealed. Queries added where identity or existence may be questionable.]
AnticlineSyncline
Fault -- Includes strike-slip, normal, reverse, oblique, and unspecified slip
Contact
County boundary
M
F
Folds -- Showing direction of plunge where appropriate
Road
SYMBOL EXPLANATION
Contacts
Stream
Reference contact -- Used to delineate geologic units that were mapped asseparate units on the original source map, but are consolidated on this map.
July 2010
Peter D. Roffers and Trinda L. Bedrossian, CEG Compiled from existing sources by
Solomon McCrea and Barbara WanishDigital preparation by
A Project for the Department of Water Resources by the California Geological Survey
SCALE 1:100 000
CONTOUR INTERVAL 50 METERSNATIONAL GEODETIC VERTICAL DATUM OF 1929
5000 0 5000 10000 15000 20000 25000 30000 35000 40000 45000 50000 FEET
5 0 52.5 MILES
050005 0 5 102.5 KILOMETERS
METERS5000 10000
W Wet area
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CHARNOCK FAULT
OVERLAND AVENUE
NEWPORT - INGLEWOOD FAULT ZONE
NEWPORT - INGLEWOOD FAULT ZONE
NEWPORT - INGLEWOOD FAULT ZONE
PA L O S V E R D E S F A U LT Z O N E
CABRILLO FAULT
WHITTI ER FAULT
LOS ALAMITOS FAULT
Los A
ngele
s Rive
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Rio Hondo
Compton Creek
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Bell GardensCudahy
InglewoodSouth Gate
Santa FeSprings
Downey
Lynwood
La MiradaEl Segundo Hawthorne
Norwalk
Compton
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Gardena
Lawndale BellflowerManhattan Beach
ArtesiaHermosa Beach
Lakewood
Redondo Beach
Torrance HawaiianGardensCarson
Lomita
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La Palma
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Los Alamitos
Westminster
Marina Del Rey
Seal Beach
Los Angeles
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Anaheim
Los Altos
RossmoreGarden Grove
San Pedro
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LOS ANGELESORA NGE
þ103þ1
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AbaloneCove
Bluff Cove
Long Beach
Middle Harbor
Lunada Bay
Malaga Cove
Outer Harbor
S a n t a M
o n i c a B a y
Flat RockPoint
LongPoint
PortugueseBend
Resort Point
Ven i ce Beach
WhitesPoint
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PointFermin
Huntington City Beach
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White Island
Freeman Island
Chaffee Island
Grissom Island
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L O S A N G E L E S B A S I N
Verdes
Hills
Del ReyLagoon
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118°35'
33°55' 33°55'
33°50' 33°50'
33°45' 33°45'
33°40' 33°40'
33°35' 33°35'
33°30'33°30'
34°118°
34°
118°
MAP UNITS
Late Holocene (Surficial Deposits)
Holocene to Late Pleistocene (Surficial Deposits)
Late to Middle Pleistocene (Surficial Deposits)
Middle to Early Pleistocene (Surficial Deposits)
Quaternary (Bedrock)
Tertiary (Bedrock)
Mesozoic and Older (Bedrock)
Artificial Fill - deposits of fill resulting from human construction, mining, or quarrying activities; includes engineered fill for buildings, roads, dams, airport runways, harbor facilities, and waste landfillsaf
Beach Deposits - unconsolidated marine beach sediments consisting mostly of fine- and medium-grained, well-sorted sandQb
Young Alluvial Fan Deposits - unconsolidated to slightly consolidated, undissected to slightly dissected boulder, cobble, gravel, sand, and silt deposits issued from a confined valley or canyonQyf
Young Alluvial Valley Deposits - unconsolidated to slightly consolidated, undissected to slightly dissected clay, silt, sand, and gravel along stream valleys and alluvial flats of larger rivers
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Old Alluvial Fan Deposits - slightly to moderately consolidated, moderately dissected boulder, cobble, gravel, sand, and silt deposits issued from a confined valley or canyonQof
Old Alluvial Valley Deposits - slightly to moderately consolidated, moderately dissected clay, silt, sand, and gravel along stream valleys and alluvial flats of larger riversQoa
Old Lacustrine, Playa, and Estuarine (Paralic) Deposits - slightly to moderately consolidated, moderately dissected fine-grained sand, silt, mud, and clay from lake, playa, and estuarine deposits of various typesQol
Very Old Alluvial Fan Deposits - moderately to well-consolidated, highly dissected boulder, cobble, gravel, sand, and silt deposits issued from a confined valley or canyonQvof
Coarse-grained Tertiary age formations - primarily sandstone and conglomerateTssFine-grained Tertiary age formations - includes fine-grained sandstone, siltstone, mudstone, shale, siliceous and calcareous sedimentsTsh
Tertiary age formations of volcanic originTvTv
Lacustrine, Playa, and Estuarine (Paralic) Deposits - mostly unconsolidated fine-grained sand, silt, mud, and clay from fresh water (lacustrine) lakes, saline (playa) dry lakes that are periodically flooded, and estuaries; deposits may contain salt and other evaporites
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Alluvial Valley Deposits - unconsolidated clay, silt, sand, and gravel recently deposited parallel to localizedstream valleys and/or spread more regionally onto alluvial flats of larger river valleys; sandy sediment generally more dominant than gravelly sediment
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Fine-grained formations of Pleistocene age and younger - includes fine-grained sandstone, siltstone, mudstone, shale, siliceous and calcareous sedimentsQsh
Eolian and Dune Deposits - unconsolidated, generally well-sorted wind-blown sand; may occur as dune forms or sheet sand
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Landslide Deposits - may include debris flows and older landslides of various earth material and movementtypes; unconsolidated to moderately well-consolidatedQls
Young Lacustrine, Playa, and Estuarine (Paralic) Deposits - unconsolidated to slightly consolidated, undissected to slightly dissected fine-grained sand, silt, mud and clay from lake, playa, and estuarine deposits of various types
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Qw Alluvial Wash Deposits - unconsolidated sandy and gravelly sediment deposited in recently active channelsof streams and rivers; may contain loose to moderately loose sand and silty sand
Coarse-grained formations of Pleistocene age and younger - primarily sandstone and conglomerateQss
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CORRELATION OF MAP UNITS
Late Holocene
Holocene toLate Pleistocene
Late to Middle Pleistocene
Middle to Early Pleistocene
Quaternary(Bedrock)
Tertiary(Bedrock)
Artificial FillLandslideDeposits
BeachDeposits
AlluvialWash
DepositsAlluvial
FanDeposits
AlluvialValley
Deposits
Lacustrine, Playa, and EstuarineDeposits
Eolian and Dune Deposits
Cretaceous andPre-Cretaceous
Metamorphic(sedimentaryand volcanic)
Coarse-grained
Fine-grained
Volcanic
Alluvial Deposits
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pKm
Quate
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Mesozoic and Older (Bedrock)
* Boundaries of Quaternary units are gradational and time transgressive in a regional sense.
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Cretaceous and pre-Cretaceous metamorphic formations of sedimentary and volcanic originpKm
www.conservation.ca.gov/cgsThe Department of Conservation makes no warranties as to thesuitability of this product for any particular purpose.Copyright 2010 by the California Department of Conservation.All rights reserved. No part of this publication may be reproduced without written consent of the California Geological Survey.Information on this map is not sufficient to serve as a substitute for the geologic and geotechnical site investigations required under Chapters 7.5 and 7.8 of Division 2 of the California PublicResources Code.
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